Compact antenna arrangement of radar system for detecting internal organ motion

Abstract

A compact radar system for detecting displacement of an internal organ of a patient in a medical scanner. The system includes at least one transmitting antenna and at least one receiving antenna located in a bed arrangement that supports the patient. In particular, the receiving antenna is located a predetermined distance from a patient reference location to enable detection of electromagnetic energy reflected from a region of the internal organ undergoing asymmetric displacement. The system further includes a radar energizing system that energizes the transmitting and receiving antennas wherein the transmitting antenna irradiates a volume of the patient's body that includes the internal organ. In addition, the receiving antenna detects the reflected electromagnetic energy from the region of the internal organ undergoing asymmetric displacement to enable determination of inhalation and exhalation by the patient.

We claim: 
     
         1 . A compact radar system for detecting displacement of an internal organ of a patient in a medical scanner, comprising:
 at least one transmitting antenna and at least one receiving antenna located underneath the patient, wherein the receiving antenna is located a predetermined distance from a patient reference location to enable detection of asymmetric displacement of the internal organ; and   a radar energizing system that energizes the transmitting and receiving antennas wherein the transmitting antenna irradiates a volume of the patient's body that includes the internal organ and the receiving antenna detects the asymmetric displacement of the internal organ to enable determination of inhalation and exhalation by the patient.   
     
     
         2 . The system according to  claim 1 , wherein the internal organ is a thoracic diaphragm and the asymmetric displacement occurs at a tip of the thoracic diaphragm. 
     
     
         3 . The system according to  claim 1 , wherein the predetermined distance is determined statistically based on measurements of a distance between the patient reference location and a tip of a thoracic diaphragm in a plurality of patients. 
     
     
         4 . The system according to  claim 3 , wherein a cardiac signal is detected simultaneously with a respiration signal of the patient wherein the detected cardiac signal is used to optimize placement of the receiving antenna relative to the tip of the thoracic diaphragm. 
     
     
         5 . The system according to  claim 1 , wherein the patient reference location is an ear canal of the patient. 
     
     
         6 . The system according to  claim 1 , wherein a substrate for each antenna has a relatively high dielectric constant to provide compact low gain antennas. 
     
     
         7 . The system according to  claim 1 , wherein the transmitting and receiving antennas are located in a mat positioned underneath the patient. 
     
     
         8 . A compact radar system for detecting displacement of an internal organ of a patient in a medical scanner, comprising:
 at least one transmitting antenna and at least one receiving antenna located in a bed arrangement that supports the patient, wherein the receiving antenna is located a predetermined distance from a patient reference location to enable detection of electromagnetic energy reflected from a region of the internal organ undergoing asymmetric displacement; and   a radar energizing system that energizes the transmitting and receiving antennas wherein the transmitting antenna irradiates a volume of the patient's body that includes the internal organ and the receiving antenna detects the reflected electromagnetic energy from the region of the internal organ undergoing asymmetric displacement to enable determination of inhalation and exhalation by the patient.   
     
     
         9 . The system according to  claim 8 , wherein the internal organ is a thoracic diaphragm and the asymmetric displacement occurs at a tip of the thoracic diaphragm. 
     
     
         10 . The system according to  claim 8 , wherein the predetermined distance is determined statistically based on measurements of a distance between the patient reference location and a tip of a thoracic diaphragm in a plurality of patients. 
     
     
         11 . The system according to  claim 10 , wherein a cardiac signal is detected simultaneously with a respiration signal of the patient wherein the detected cardiac signal is used to optimize placement of the receiving antenna relative to the tip of the thoracic diaphragm. 
     
     
         12 . The system according to  claim 8 , wherein the patient reference location is an ear canal of the patient. 
     
     
         13 . The system according to  claim 8 , wherein a substrate for each antenna has a relatively high dielectric constant to provide compact low gain antennas. 
     
     
         14 . The system according to  claim 8 , wherein the bed arrangement includes a mat that includes the transmitting and receiving antennas. 
     
     
         15 . A method for locating a receiving antenna in a radar system that detects displacement of an internal organ of a patient in a medical scanner, comprising:
 measuring a distance between a patient reference location and a region of the internal organ that moves asymmetrically, wherein the distance is measured in a plurality of patients to provide a plurality of measured distances;   calculating a statistical measure for the measured distances to determine a calculated distance; and   locating the transmitting antenna in a patient bed wherein the transmitting antenna is spaced apart from the patient reference location by the calculated distance.   
     
     
         16 . The method according to  claim 15 , wherein the internal organ is a thoracic diaphragm and the asymmetric displacement occurs at a tip of the thoracic diaphragm. 
     
     
         17 . The method according to  claim 16 , further including detecting a cardiac signal simultaneously with a respiration signal of the patient wherein the detected cardiac signal is used to optimize placement of the receiving antenna relative to the tip of the thoracic diaphragm. 
     
     
         18 . The method according to  claim 15 , wherein the patient reference location is an ear canal of the patient. 
     
     
         19 . The method according to  claim 15 , further including positioning a mat that includes the transmitting and receiving antennas between the patient and the patient bed. 
     
     
         20 . The method according to  claim 15 , wherein a substrate for each antenna has a relatively high dielectric constant to provide compact low gain antennas.